Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Cardiovascular System > ECGs > Flashcards

ECGs Flashcards

(106 cards)

Start Studying
1
Q

Where is the SA node located?

A

Top right hand corner of right atrium

near junction of SVC and right atrium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Why is the SA node specialised?

A

Myocytes do not contract
They spontaneously depolarise
to generate action potentials

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the SA node known as?

A

Pacemaker of heart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Why is the SA node the pacemaker of the heart?

A

Beause it spontaneously depolarises faster than other parts of the electrical conducting system
So it sets the rhythm of the heart beat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is it called when the SA node sets the rhythm of the heart beat?

A

Sinus rhythm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What happens after the SA node generates an action potential?

A

Wave of depolarisation spreads across internodal pathways and atrial myocytes, downwards and to left

Depolarised atrial myocytes contract

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Where is the AV node located?

A

Interatrial septum

Above the tricuspid valve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What happens during depolarisation of the atrial myocytes and their contraction?

A

Action potential is held up at AV node

AV node delay

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the purpose of AV node delay?

A

To allow time for all the atria to depolarise and contract

Emptying the atria, filling the ventricles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Wher doere does the AV node conduct the action potential to?

A

Down the bundle of His

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Where is the bundle of His located?

A

Beginning of the interventricular septum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the only electrical conducting pathway between the atria and ventricles?

A

The bundle of His

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Why is the bundle of His the only electrical conducting pathway between the atria and ventricles?

A

Because of fibrous rings between the atria and ventricles

non-conductive tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What does the bundle of His divide into?

A

Right bundle branch

Left bundle branch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Where do the right and left bundle branches lie?

A

Interventricular septum

sub-endocardially - just beneath endocardium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Where do the right and left bundle branches carry the action potential to?

A

Down the interventricular septum

to the apex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How does the interventricular septum depolarise?

A

From left to right

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What carries the action potential from the apex of the heart?

A

Purkynje fibres

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Where are the purkinje fibres located?

A

Walls of ventricles

sub-endocardially

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Where do the purkinje fibres carry the action potential to?

A

Up the ventricular walls, to the base of the ventricles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How does the myocardium of the ventricles depolarise? Why?

A

From endocardium to epicardium

since bundle branches, His purkinje system lie sub-endocardially

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is an important feature of the His-purkinje system?

A

Carry action potentials extremely fast, almost simultaneously
So ventricular myocytes depolarise and contract in a synchronised way

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the overall direction of depolarisation?

A

Towards the apex of the heart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the order of contraction in the heart?

A 
Atrial myocytes
Septum - left to right
Apex
Walls of ventricles - endocardium to epicardium
Base of ventricles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What is the order by which cardiomyocytes repolarise?
The opposite to the order by which they depolarised Base of ventricles Walls of ventricles - epicardium to endocardium Apex Septum - right to left
26
What does an ECG record?
Changes occurring on extracellular surface of cardiomyocytes during depolarisation and repolarisation
27
How is the ECG set up?
Electrodes placed on skin
28
If wave of depolarisation is moving towards a positive electrode, how does this show on an ECG?
Positive complex
29
If wave of depolarisation is moving away from a positive electrode, how does this show on an ECG?
Negative complex
30
If wave of repolarisation is moving towards a positive electrode, how does this show on an ECG?
Negative complex
31
If wave of repolarisation is moving away from positive electrode, how does this show on an ECG?
Positive complex
32
Why do deflections eventually return to the baseline?
Change takes over more than half of cardiomyocytes | Becoming more similar, change decreasing
33
What does a flat line on an ECG mean?
No significant electrical activity occurring in heart | No change on surface of caridomyocytes
34
If a wave of depolarisation is travelling directly towards a positive electrode, how does show on an ECG?
Tall positive complex
35
If a wave of depolarisation is travelling at an angle towards a positive electrode, how does this show on an ECG?
Shorter positive complex
36
If a wave of depolarisation is travelling perpendicularly towards a positive electrode, how does this show on an ECG?
Small biphasic complex - positive then negative | or no complex
37
How does depolarisation of the SA node show up on an ECG? Why?
Flat line, baseline | Insufficient electrical activity to be picked up by ECG
38
How does depolarisation of the atria show up on an ECG? Why?
Produces small positive complex Because wave of depolarisation is moving towards positive electrode at apex, at an angle Shows up because is large muscle mass depolarising
39
What is the ECG wave corresponding to atrial depolarisation?
P wave
40
How does the AV node delay show up on an ECG?
Flat line, baseline | called segment 1b
41
How does depolarisation of the His-purkinje system show up on an ECG?
Flat line, baseline | still segment 1b
42
How dows depolarisation of the interventricular septum show on an ECG? Why?
Short negative complex Because moving away from positive electrode at apex, at an angle Shows up because is large muscle mass depolarising
43
What does depolarisation of the interventricular septum correspond to on an ECG?
Q wave
44
How does depolarisation of the apex and ventricular wall show up on an ECG?
Tall positive complex Because depolarisation moving directly towards positive electrode at apex Also because large muscle mass is depolarising
45
Which wave on an ECG corresponds to depolarisation of the apex and ventricular walls?
R wave
46
In LV hypertrophy, how is the R wave different? Why?
Taller | due to larger muscle mass depolarising
47
How does depolarisation of the base of the ventricles show up on an ECG?
Short negative complex Because moving away from positive electrode at apex, but at an angle
48
Which wave on an ECG corresponds to depolarisation of the base of the ventricles?
S wave
49
How does ventricular repolarisation show up on an ECG?
Medium positive complex Because repolarisation is moving away from positive electrode at apex at an angle
50
Which wave on an ECG corresponds to repolarisation of the ventricles?
T wave
51
How many electrodes are placed on the skin in an ECG?
Ten
52
What are the ten ECG electrodes divided into?
Four on the limbs Six on the chest
53
Where are each of the four limb electrodes placed?
Right arm - red Left arm - yellow Left leg - green Right leg - black
54
What is a lead?
Refers to view of the heart
55
How many views do the four limb leads give?
Six
56
What can the six limb lead views be divided into?
Unipolar leads Bipolar leads
57
What are the unipolar leads?
aVF aVR aVL
58
What are the bipolar leads?
Lead 1 Lead 2 Lead 3
59
What are the positive and negative poles with the unipolar limb leads?
Positive pole is one electrode, see from here Negative pole is average of other two electrodes, ends up being heart
60
What does avF look at?
Heart from left leg | its inferior surface
61
What does avR look at?
Heart from right arm
62
What does aVL look at?
Heart from left arm | its left lateral surface
63
What are the degrees of aVF, aVL, aVR?
``` aVF = 90degrees aVR = -150degrees avL = -30degrees ```
64
What are the positive and negative poles with the bipolar limb leads?
Positive pole is one electrode Negative pole is another electrode
65
What are lead 1's poositive and negative poles?
Left arm is positive pole Right arm is negative pole
66
What are lead 2's positive and negative poles?
Left leg is positive pole Right arm is negative pole
67
What are lead 3's positive and negative poles
Left leg is positive pole Left arm is negative pole
68
What does lead 1 look at?
Heart from left arm | its left lateral surface
69
What do leads 2 and 3 look at?
Heart from left leg | its inferior surface
70
What are the degrees of Leads 1, 2, and 3?
Lead 1 = 0 degrees Lead 2 = 60 degrees Lead 3 = 120 degrees
71
The limb leads view the heart in what plane?
Coronal plane - vertical
72
Where are each of the six chest electrodes placed?
V1 - 4th intercostal space, right sternal border V2 - 4th intercostal space, left sternal border V3 - between V2 and V4 V4 - 5th intercostal space, mid-clavicular line V5 - between V4 and V6 V6 - 5th intercostal space, mix-axillary line
73
What are V1 and V2 called?
The septal leads
74
What do leads V1 and V2 look at?
Right ventricle and septum
75
What are V3 and V4 called?
The anterior leads
76
What do V3 and V4 look at?
Anterior wall of ventricles | apex
77
What are V5 and V6 called?
Lateral leads
78
What do V5 and V6 look at?
Left ventricle
79
Why do each of the chest leads produce different ECGs?
At different angles to heart | Waves of depolarisation, repolarisation occur at different angles to each of them
80
What plane do the chest leads view the heart in?
Transverse plane - horizontal
81
If one of the chest leads is abnormal, what does this mean?
Damaged myocardium | in the area that the chest lead looks at
82
What is the size of one small square on an ECG?
1mm x 1mm
83
How long is one small square on an ECG?
0.04s
84
What is the size of one large square on an ECG?
5mm x 5mm
85
How long is one large square on an ECG?
0.2s
86
What is the horizontal axis on an ECG?
Time (s)
87
What is the vertical axis on an ECG?
Voltage (mV)
88
How many squares is 1s on an ECG?
25 small squares 5 large squares
89
How many squares is 1m on an ECG?
300 large squares
90
How is a heart rate calculated if the rhythm is regular?
Count number of boxed between two R waves | Do 300/n
91
What is a regular rhythm?
Same amount of time between cardiac cycles, one wave to next
92
How is heart rate calculated if the rhythm is irregular?
Count number of R waves in 6 seconds, 30 large squares | Multiple by 10
93
What is an irregular rhythm?
Different amounts of time between cardiac cycles, one wave to next
94
What is the PR interval?
Beginning of P wave | To beginning of Q wave
95
How long is a normal PR interval? How many squares?
0.12 - 0.20 seconds 3-5 small squares
96
What is a QRS interval?
Beginning of Q wave | To end of S wave
97
How long is a normal QRS interval? How many squares?
Less than 0.12 seconds Less than 3 small squares
98
What is the QT interval?
Beginning of Q wave | To end of T wave
99
Does the QT interval vary with heart rate? Why?
Yes | Because time in diastole varies with heart rate
100
How long is the normal QT interval? How many squares?
Males - 0.45s Females - 0.47s 11-12 small squares
101
What is sinus rhythm?
Depolarisation initiated by SA node
102
What are the criteria of sinus rhythm?
Regular rhythm Heart rate 60-100bpm P waves - upright in leads 2 and 3 - followed by QRS Normal PR interval Normal QRS interval
103
What is sinus bradycardia?
Heart rate below 60bpm
104
When is sinus bradycardia physiologically normal?
Sleeping Athletes
105
What is sinus tachycardia?
Heart rate above 100bpm
106
When is sinus tachycardia physiologically normal?
Exercise

Cardiovascular System (22 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions